This invention relates to methods and compositions for protecting materials from growth of pestiferous organisms, and particularly for preventing marine surfaces from fouling.
Organotin compounds such as trialkyl- and triarylorganotin compounds are used for control of fungi, bacteria, and marine organisms. However, their use has been limited because of certain deficiencies. For example, these compounds may be phytotoxic and possess a high mammalian toxicity. They may have a disagreeable odor and relatively high vapor pressure which limits their use in such areas or aerosol spray applications. These compounds also lack durability because they can be removed readily from a treated surface by rubbing, washing, and extraction. This is particularly true when they are used as additives in antifouling coatings for marine surfaces, where these compounds have been shown to be effective for only one to two years. This short effective life is attributed to leaching of the compounds from the coating matrix.
Leebrick in U.S. Pat. No. 3,167,473, describes biologically active polymers obtained by polymerizing a compound having the formula R.sub.3 SnOCR' where R is an alkyl or phenyl radical and R' is a polymerizable organic group such as the vinyl radical. Although Leebrick's polymers are more durable than organotin compounds by themselves, these polymers have limited strength and durability and can exhibit incompatibility with inorganic zinc coatings, which are commonly used to provide corrosion resistance to marine surfaces.
Thus there is a need for biologically active materials for forming coatings to protect materials such as marine surfaces against the growth of pestiferous organisms where the coating has improved strength, longer antifouling service life, and is compatible with inorganic zinc coatings. An additional objective is to develop biological active compounds as additives to conventional paints to provide very low leaching of the toxicant and thus longer service life to the antifouling paint.